1. Field of the Invention
The present invention relates in general to a lubrication for a horizontal type hermetic compressor and, more particularly, to a lubricating device for the horizontal type hermetic compressor.
2. Description of the Prior Art
As well known to those skilled in the art, hermetic compressors are generally classified into two types, that is, vertical type hermetic compressors and horizontal type hermetic compressors. The above classification of the hermetic compressors is according to location of their crank shafts. Otherwise stated, the crank shafts of the vertical type compressors are vertically positioned while the crank shafts of the horizontal type compressors are horizontally positioned. However, the hermetic compressors irrespective of their types should be provided with lubricating devices for supplying lubrication oil to their driving parts such as the crank shafts.
With reference to FIG. 1A, there is schematically shown a construction of a typical hermetic compressor of the vertical type. The vertical type hermetic compressor is encased by a vertical compressor casing 1a which is charged with lubrication oil "o" in its lower section. The lubrication oil surface is nearly leveled to a cylinder 2 as well as a main bearing 5a which are encased in the compressor casing 1a at the lower section of the casing 1a. The cylinder 3 receives a crank shaft 4a which has an oil port 5 provided with a lubricating propeller (not shown). When the crank shaft 4a is rotated in the cylinder 3, the lubricating propeller provided at the oil port 5 is also rotated in order to supply the lubricating oil "o" to the driving parts of the compressor.
Turning to FIGS. 1B and 1C, there is shown a construction of a typical horizontal type hermetic compressor. This compressor has a crank shaft which is horizontally positioned in a horizontal compressor casing 1 such that its axis is coaxial with the center axis of the casing 1. A lubricating device of this horizontal type hermetic compressor comprises a rotating shaft 4 which is concentrically received in a cylindrical cavity of a cylinder 2 defining a compression chamber C therein. The rotating shaft 4 is also coupled to an eccentric roller 3. The cylinder 2 is coupled at its both sides to a main bearing 5 and a sub bearing 6, respectively, which support the rotating shaft 4 at opposed sides of the cylinder 2 and define the compression chamber C in cooperation with the inner surface of the cylinder 2. The cylinder 2 also includes an oil pumping chamber 9 communicating with the inside of the casing 1 and pumping the lubrication oil "o" in the casing 1 in order to supply the oil to the driving parts of the compressor. The oil pumping chamber 9 is provided with an oil inlet-side hydraulic diode 10 at one side thereof corresponding to the main bearing 5 and with an oil outlet-side hydraulic diode 11 at the other side thereof corresponding to the sub bearing 6. A spring-biased vane 7 is radially received in the oil pumping chamber 9 such that its distal end comes into close contact the outer surface of the eccentric roller 3. When the eccentric roller 3 coupled to the shaft 4 is eccentrically rotated in the cavity of the cylinder 2 by the rotation of the shaft 4, the spring-biased vane 7 coming into close contact with the roller 3 elastically advances and retracts by the eccentric rotation of the roller 3. Thus, the lubrication oil "o" in the casing 1 flows in the oil pumping chamber 9 through the oil inlet-side diode 10 and, thereafter, is delivered to the driving parts of the compressor, such as the rotating shaft 4, through the oil outlet-side diode 11. The communication of the oil outlet-side diode 11 with the rotating shaft 4 is achieved by an oil feed pipe 12 connected therebetween.
In operation of the above horizontal type hermetic compressor, the eccentric rotation of the roller 3 coupled to the rotating shaft 4 makes the spring-biased vane 7 elastically advance and retract, thus to cause a change of inner volume of the oil pumping chamber 9 as well as an oil pressure difference between the pumping chamber 9, the oil feed pipe 12 and the inside of the casing 1. Hence, the lubrication oil "o" charged in the lower section of the casing 1 is forcibly supplied to the rotating shaft 4 through the oil inlet-side diode 10, the oil pumping chamber 9, the oil outlet-side diode 11 and the oil feed pipe 12.
Otherwise stated, when the vane 7 advances towards the cavity of the cylinder 2, the volume occupied by the vane 7 in the pumping chamber 9 is reduced and this causes generation of negative pressure in the pumping camber 9. The lubrication oil in the casing 1 is thus sucked into the pumping camber 9 through the oil inlet-side diode 10. At this time, the lubrication oil intending to reversely flow from the feed pipe 12 to the pumping chamber 9 is limited in its amount to be very small since the oil outlet-side diode 11 is reversely positioned. When the vane 7 retracts from the cavity of the cylinder 2, the inner volume of the pumping camber 9 is reduced and, as a result, the oil in the chamber 9 is compressed. The lubrication oil under pressure is thus delivered to the rotating shaft 4 through the oil outlet-side diode 11 and the feed pipe 12. At this time, the lubrication oil intending to reversely flow from the pumping chamber 9 to the inside of the casing 1 is limited in its amount to be very small since the oil inlet-side diode 10 is reversely positioned. A predetermined amount of lubrication oil, that is, the difference between the amount of the lubrication oil flowing out through the oil outlet-side diode 11 and the amount of the lubrication oil flowing out through the oil inlet-side diode 10, is supplied to the friction parts of the driving parts of the compressor.
However, the conventional horizontal type hermetic compressor has a problem that since its compression chamber is defined by the cylinder 2, the main bearing 5 and the sub bearing 6, it can not use the cylinder, the main bearing and the sub bearing of the conventional vertical type hermetic compressor. Another problem of the conventional hermetic compressor is resided in that the delivery amount of the lubrication oil is determined by the geometrical characteristics of the oil inlet-side and oil outlet-side hydraulic diodes, so that it is difficult to control the flow rate of the lubrication oil.